Add files to iPad 3 from hard drive

I am new to the mac world. I had figured out how to put my videos, music, book files from my hard drive to the apps I have purchased for the IPAD3, pdfExpert, GoodPlayer, Bluefire, flacplayer, etc. Thru Itunes I would go to my IPAD, go to the particular app I wanted to copy to, and then access my harddrive to pick the things I wanted to transfer. Not a question of having everything taken and put on IPAD, just the ones I selected in any folder I wanted from my harddrive.

Today I went to do this again and could not figure out how to do I kept ending up at the store to buy something. I do not want to buy anything.

How do I do what I had been doing before, put my stuff in the folders that come with these apps in Ipad.

I searched the site, but saw nothing but if there is some directions, please point me to them.

If they are files you're trying to add so that a certain app can utilize them, you have to do it from the 'Apps' section of iTunes with your device plugged in. Just go to the 'Apps' section and scroll to the bottom. Find the app you want to add files to and select it, then browse to your files.

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